it's definitely saturated right now, that's true. but so was 2017 vs 2014 (the first alt spring). it's also less about saturation of the entire altcoin market and more about what's listed on relevant exchanges. lots of shit tokens and shitcoins don't get ever get listed anywhere---no point worrying about those.
at the moment, i couldn't tell you, because i haven't looked at the alt market in 6+ months. that's a lifetime in crypto. i'll be doing significant research when i see accumulation across the market and the beginnings of a bull run. see what the twittersphere and prominent altcoin miners are watching, hash rate fundamentals, hype/marketing propensity (this is key), supply analysis, sector analysis, etc. i would watch for sector rotation like stock markets; i noticed this in 2017. DEX and privacy coins are two areas i expect to blow up during the next run.
the big gainers are going to be micro-caps and low-caps. i might allocate some portfolio space to large cap coins when the alt spring is in full swing, but i emphasize spreading funds around to <$10-20 million cap coins. the large caps have already seen the "big gains" so their volatility declines, similar to BTC.
some of my coins will go nowhere i'm sure but a couple big trades will eclipse the losses/lack of gains from those. i'm also not worried about "real fundamentals" so much. i'm not looking for long term holds here. i'm just trying to ride pumps while the market is hot.