what coin do you think i should invest in and why?
What do you value in a coin? I ask because a coin should be a long-term commitment; the same way if you're investing in a stock: once you decide to invest in a stock, you should then follow that stock's news, updates, quarterly reports, incoming and outgoing personnel, R&D, competitors, ect....
Find the one(s) that fits your needs and start researching. The monetary investment is only the beginning stage to what should be a mutually beneficial relationship.
I'm assuming when you say invest that you mean investing and not trading--which are two different skill-sets that sometimes, but not always, overlap.