yeh im currently using an ego 1100 mah, the coils i use are 2.5 ohms,
So if your eGo is a fixed voltage battery then you're vaping at about 6Watts which is a little underpowered. Most people wind up prefering a vape at around 8Watts power, though some people prefer higher power settings and some people prefer lower power than that.
What's your budget?
If cost is the single biggest factor then buy a Vamo from somehwere like FastTech. you'll wait anywhere up to a month for delivery (usually around 2 weeks) and their customer service is 'hit and miss' but you won't get a cheaper deal anywhere. If you value being able to pick up the phone and talk to someone that knows what they are talking about and you want an item in your hands the next day, then get a Vamo from a UK vendor. Any of the vendors on POTV are likely to be decent ones. If you live close enough to a vape shop then go visit one and ask to try out some stuff (if they say no - then walk away the shops a bad one)
The best way forwards is to get yourself a cheap regulated device that has variable voltage/variable wattage on it and play around with different power settings to see what style of vape you like the best. There are a bunch of similarly priced regulated 'batteries' out there a Zmax a SID an SVD or a Vamo all do the same thing with different styling, all are around £40-£50 from a UK vendor. A protank will sit nicely on top of any of them and will give you a decent vape no matter what ohm coil you have in them (though I'd recommend using no higher than 2ohm coils 2.5ohm is a little high) If you buy a kit with batteries and a charger then make sure you get a good charger right off the bat. The Trustfire charger is decent but I wouldn't get anything cheaper than that, the XTar or NiteCore chargers are better still.
£50 is approximately 7 packets of 20 fags, or 7 pouches of rolling baccy if you've quit smoking and moved to vaping then YAY! welldone, it's worth bearing in mind how the costs of vaping compare to smoking when working out how much you want to spend on things. Once you get past the initial outlay for things then running costs are a lot lower, even if you buy replacement heads off the shelf and premixed e-liquid.
At the end of the day if you plan on keeping vaping for a while you will want to have a backup device (or two) so buying a cheapish regulated device isn't a waste of money as even if you move onto some other device later on it'll be handy to have something like a Vamo around for testing coil resistances, having a different flavour ready to go at home, having another device if your main one breaks for any reason etc. The main advantage of devices where you insert batteries is that eventually batteries wear out and if your eGo battery wears out you need a whole new eGo, if the 18650 in your mod wears out you can just replace it pretty cheaply.
So bottom line, get yourself a Vamo, a Zmax, a SID or an SVD to go with your ProTank, and play about with power settings. It'll cost you £50 or so upfront, but the difference in quality of vape will be well worth it.