Avoid any coin that has a high total and a seemingly low premine %. Warning bells should alarm that it's likely a pump and dump altcoin.
There appears to be a trend towards meme coins right now, so Doge would be a safe bet if you wanted an altcoin with return. For long term investment, personally I'd avoid scrypt. Maybe a quark-based coin. Certainly investing in at least one of each wouldn't harm.
What makes scrypt coins less reliable in the long run? What would you say about DTC?
Well, I'm not saying less reliable, just less stable. The market is flooded, and with some "supposed" ASIC chips being developed for scrypt (which right now I highly doubt, but I do think it's a matter of time), then eventually the Scypt market is going to see a flood, and basically any new scrypt coin will be mined so fast and hard that it just won't be worth mining.
The way to invest now would be in a scrypt coin that you think will still be going strong in a year or two. If ASICs ever do appear for scrypt, then that coin's value is bound to go up, and with a good userbase behind it hopefully ride out the currency fluctuations when it happens.
I'm not too familiar with DTC. Some of these novel coins are interesting, but when everything's *new*, almost any change is a novelty, and there are a few novel coins out there already. Certainly would be safer to hedge your bets and invest in a few scrypt coins, and then maybe a quark coin. Or some form of combination algorithm that can only be mined by CPU.
