Where will you be using them? The EP630s and JVCs will be a lot easier to get in and out than the iM616s, especially if you will only be using them a short time. However, the iM616s isolate better, so if you want to use them mowing or on a plane they'll be better. For working out the former 2 would be.
I'm not a bass-head, so I find the EP630's and JVC's bass a bit boomy, but it's not bad. The iM616s are on the other side - a little lean, though the seal has a lot to do with it. The iM616s are a lot more detailed and sound very good, but I use the others for working out because I care less about breaking them, and also they don't isolate as much and are easier to get in and out of my ears.
For me, the JVCs stock tips did not work at all, but now that I have the E2C soft-flex tips on them they work very well. I also Kramer-modded them, which I think makes them much more lively. Before they were a bit boring for the rock and metal I listen to. It also makes them pretty similar to the EP630s. The EP630s softer tips are more comfortable, but a bit harder to get just right. At this point I don't know that I prefer one over the other by any great margin.