1.5 watt is better than 0.5 watt, however that will only help you reach other people. If you need to HEAR what's going on you need a bigger or better antenna. Not sure which one of those will have the better antenna, probably the most exxy one but that's not guaranteed
Any of those do the job fine, but as milo says you do lose out on signal if you're in a big group or there's distance between cars.
I've got an ICOM IC-40s which retails new for $400, but picked mine up second hand for a lot less than that. It's as good a handheld as you're going to get, and you can take it out of the car or hide it so you don't attract thieves. I will eventually upgrade to a proper mobile rig and keep the handheld for when I am outside the car. It's only really necessary to get a mobile CB if you do a fair bit of cruising though, for starters I'd just grab a cheapie and when it starts holding you back, upgrade.