I will first start by saying that it all depends on how experience the investor is in cryptocurrency, if you are running away from taking risk and you're being experienced or newbie in cryptocurrency, you should go for bitcoin then you may later choose to add some few altcoins you know about, what we should always go after is not in the amount Invested, but on what we have used of financial hard earned resources to invest upon.
bitcoin for long term, can't go wrong with it, but if its for lesser capital some other altcoin also might do, after all we are seeking profit here and depends on the term of investment investing in a big coin might not necessarily be effective.
some people said that investing in new project might do, well considering the fact that new project always have the trend to go up indeed they might be a good investment after all it can turn small money into big one just by investing in the right project.
meanwhile there's also not wrong if we can be patience enough to wait for big coin like bitcoin and ethereum rise we also might get profit but don't expect too much from small capital, these two asset shine bright when our capital is big, since they are relatively safe if compared to other as you have stated earlier also the fact that their bullrun is almost obvious is a good bet.