I would second a pico, the 75 watt version over an Istick. I actually have a very elderly one that was a gift from someone here (it's 30 watts) and it's an excellent mod, I mean it's still kicking and etc. It's just that really, you would probably want more capacity at the wattage ranges you are mentioning, also you would have the ability to just switch out your battery as needed (it would be safest to get an external charger, honestly) if you buy a couple of batteries.
If you are dead set on an internal battery, there's the Asipire zelos, it goes to 75 watts. It was one of my starter setups and it has been durable and reliable. You will still need to deal with the charging vaping issue. I know passtthrough is a thing, it's not exactly my favorite thing though, (IMO) it can overstress a battery.
But at the end of the day, you will be vaping it, so you should go with what makes most sense to you and appeals to you, etc.
Anna