Find a middle ground with midcap ETFs.

Many investors tend to think that bigger is better — but they overlook the middle category of publicly traded stocks that are neither so large that their best growth days are behind them nor so small that one bad quarter will cause disaster. These so-called "midcap" companies are typically valued between $2 billion and $10 billion. In some ways, they are the "Goldilocks" approach to investing with growth potential and a measure of stability, with reasonably deep pockets but untapped markets ahead. If you're looking to invest in this middle ground of midcap stocks, here are eight different exchange-traded funds, or ETFs, that can provide easy access to this slice of the stock market.

iShares Core S&P Mid-Cap ETF (ticker: IJH)

With almost $64 billion in assets under management, this iShares fund is the go-to way for many investors to play midsize stocks. IJH is benchmarked to the S&P MidCap 400 index — that is, the next 400 stocks that come after you line up the top stocks in the more popular S&P 500 large-cap index. Top stocks right now include midsize genomics company Bio Techne (TECH) and regional financial stock Signature Bank (SBNY), to name a few. This midcap ETF also comes with a rock-bottom annual expense ratio of 0.05%, or $5 for every $10,000 invested.

Vanguard Mid-Cap ETF (VO)

Similar to the prior iShares fund, the Vanguard Mid-Cap ETF is comprised of about 370 stocks instead of 400 and is benchmarked to the CRSP US Mid Cap Index — a grouping developed by the Center for Research in Security Prices at the University of Chicago Booth School of Business. When it comes to assets under management, this Vanguard fund is also very popular at roughly $50 billion in total cash right now. Sector weightings are slightly different, however, with technology making up the top sector in VO at nearly 18% while industrials lead IJH at 18%. Top holdings include maker of veterinary and livestock products Idexx Laboratories (IDXX) and managed care company Centene Corp. (CNC).

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iShares Russell Mid-Cap ETF (IWR)

Last but not least among the leading midcap ETFs out there, this $30 billion iShares offering provides exposure to the Russell Midcap Index. This listing's portfolio is obviously much deeper than either of the prior funds' portfolios, but it's actually more inclusive of slightly bigger stocks as well as slightly smaller ones. Specifically, the index is formulated by taking the top 1,000 stocks of the Russell 1000 Index ranked by market capitalization and omitting the 200 largest names. As a result, you get exposure to some rather large names, such as social media giant Twitter (TWTR), which is valued at $50 billion and may not be considered "midsize" in the eyes of many, as well as smaller industrial, technology and consumer discretionary plays.

Vanguard Mid-Cap Value ETF (VOE)

In addition to simply slicing up the market by size, there are midcap ETFs out there that layer on more qualitative screening methods. VOE is among the largest of such funds, with $15 billion under management and an approach that focuses on value metrics, including book value and return on equity. The lineup is more focused at just 200 or so total stocks at present, but value-oriented investors will prefer this more tactical approach. Generally speaking, this midcap ETF is lighter on tech and industrials than the generic funds and more heavily weighted toward financial and consumer stocks that exhibit these value metrics.

Vanguard Mid-Cap Growth ETF (VOT)

As you no doubt have guessed, the flip side of value investing is growth investing — and there's a midcap ETF for that, too. This Vanguard fund is different from the prior midcap ETF in that it is focused on about 200 stocks, but these are the companies that rank best on metrics like earnings or sales growth when compared with their peers. It may not come as a shock, then, that midsize technology companies make up about a third of the entire portfolio and sectors such as consumer staples and utilities barely even register. Top holdings include real estate firm Digital Realty Trust (DLR) and semiconductor product maker Microchip Technology (MCHP). If you like slightly smaller stocks because of the growth potential they offer, then VOT may be up your alley.

WisdomTree U.S. MidCap Dividend Fund (DON)

WisdomTree acknowledges that many investors are looking for income as well as capital appreciation, and offers the $3 billion DON fund as a way for you to focus on midsize corporations as well as dividends. Industrial stocks such as Rubbermaid manufacturer Newell Brands (NWL) and financial stocks such as midsize insurer CNA Financial Corp. (CNA) make up about 40% of the portfolio, as smaller tech companies or health care upstarts don't really have the capital to share with shareholders just yet. Interestingly, the yield on this midcap dividend fund is 2.05% compared with just 1.32% for the S&P 500 index of large-cap stocks — meaning you actually get more income potential even when you go smaller.

Nuveen ESG Mid-Cap Growth ETF (NUMG)

This Nuveen fund's focus on ESG — that is, stocks that satisfy certain environmental, social and corporate governance criteria — makes it noteworthy even if it has only got about $300 million in assets. Investing in socially responsible ways is increasingly important, so this ETF is not only worth a look because of its appeal to investors but also because institutional money is increasingly flowing into these strategies. Stocks are all midsize in NUMG, but they comprise picks like online dating giant Match Group (MTCH), which recently began publishing an annual impact report to better disclose its ESG practices and stay in line with both customers and investors on these issues.

John Hancock Multifactor Mid Cap ETF (JHMM)

If none of these specific funds tickle your fancy, then consider this John Hancock "multifactor" midcap ETF that has a more active approach to stock selection. There's a big list of total holdings, coming in at around 670 positions right now, and it's very diversified with a mere 4% or so of total assets in the top 10 positions and no single stock representing more than about 0.5% of the fund. The selection of companies is built using factors including lower relative price and higher profitability when compared with peers based on John Hancock's proprietary system. Right now, tech stocks Marvell Technology (MRVL) and Parker Hannifin Corp. (PH) top the list. Be warned, if the stock-picking strategy pays off, you'll do well, but if not, you may be better off with some of the more passive funds on this list that follow rigid rules without the guesswork.

Eight midcap ETFs to buy:

— iShares Core S&P Mid-Cap ETF (IJH)

— Vanguard Mid-Cap ETF (VO)

— iShares Russell Mid-Cap ETF (IWR)

— Vanguard Mid-Cap Value ETF (VOE)

— Vanguard Mid-Cap Growth ETF (VOT)

— WisdomTree U.S. MidCap Dividend Fund (DON)

— Nuveen ESG Mid-Cap Growth ETF (NUMG)

— John Hancock Multifactor Mid Cap ETF (JHMM)