Congratulations on the switch to vaping Rui! I can't speak to 7.4 volts; but at the 5+ volts I really like the BE112 or 302. I've only tried a 901 for a few hours but really enjoyed it. The sweet spot for me seems to be an atty with 3.0 to 3.5 ohms at 5+ volts. (around 8 or so watts)
The be112 and 302 atties are 801 style atties (801 threading) so depending on what native connector you have on any given pv, you'll need adapters. For example, if your pv has a 510 connection, then get a 510 to 801 adapter. With this set up, you'll be able to use an 801 atomizer, a mini 801 atomizer, a 302, or a be112. I really like the stealth adapters from avidvaper. There are also 510 to 901 adapters, and these are also available in the stealth adapter style as well. 510 atomizers are also available for higher voltages, and are sold as HV 510 atomizers.
Drip tips are also available for each atomizer style you choose. Again, experiment here also because each style will alter the vape somewhat. With an 801 style, for example, I really like the short open wide mouth style Delrin 801 drip tip. With 510 or 901, the shorty contoured wide mouth Delrins are very nice.
The other thing I really like at higher voltage is the jumbo kr808 cartomizers. Again adapters are available for your battery type connection to a kr808. These save me while driving. Just fill and go. These jumbo cartos hold 2 mls of liquid for when you can't repeatedly drip.
Good luck. Just experiment and find what you like best. Everyone tunes in to their own personal favorites. And enjoy!
