If you dont like the button being on top for the RoughStack, I would check out the Bolt. Its similar but has a better button placement. Its a solid PV and CCV sells it for only $37.50 which is dirt cheap.
Also check out the E-Power 14650. Its like the Riva and kGo, but uses non-proprietary batteries like a mod does. E-Power batteries cost $4-5 compared to eGo/Riva/kGo batteries that are $14-20, and the E-Power batteries last alot longer before they need to be replaced. Also everything is replaceable on the E-Power so its cheaper to maintain. The switch, batteries, and tube can all be bought seperately as apposed to the proprietary battery eGo/kGo/Rivas where if one part goes bad you have to replace the whole unit. I love my E-Power and it gives a great vape. The batteries are 1050mah and I get avg a day to a day and a half on one battery. Plus its easy to carry a spare battery bc they are small and if needed unscrew the switch and pop in a fresh battery, so you never really have to worry about getting stuck with a dead battery. Its 3.7V regulated so it gives a great consistant vape. I use the Ressurector cartos in a 3.5ml tank on mine and absolutely love it. Its under $50 bucks too so you dont have to break the bank