I've only played LoL, started playing it and liked it enough I never got around to trying out others. I can't comment on the graphics as my computer will only run on anything on the bare minimum (which will be fixed soon weeeeeeeeeee) but gameplay is fun. Probably a good time to get involved as they're in the middle of making a lot of changes for the next season of ranked play. Adding new champions, experimenting with new game modes, tweaking the current champs and modes to level gameplay, and something else that I can't remember and now it's bothering me so thanks.
It is entirely possible to play LoL without paying a cent. You can purchase Riot Points (RP) for $$$ if you want to buy frivolous things like alternative champion skins...you can also use these to purchase champions if you feel like speeding your champion acquisition up. Most place use their Influence Points (IP) which you earn after each game you play. Each week there are 10 champions that can be played by everyone for free. I can see where people prefer to have everything free from the start, but for me (both starting myself, and teaching others to play) I prefer the limit. It helps you to find a character that you like to play, and then you can work towards getting the IP to purchase it so you can always play that character. Of course as you learn you'll want to try new roles and characters, but starting out with a goal to earn and learn 1 champion goes a long way.
Also, this:
http://venturebeat.com/2013/07/27/compa … f-newerth/
<KT|Away> I am the Trump of IC