the budget seems to be the constraint…I’m assuming you are wanting something analog since you mentioned an iPad…the iPad has some wonderful soft synths…some of the synths mentioned in this thread are not analog though so not sure if that was a requirement or not

someone already mentioned the minitaur…fantastic analog synth but it shines in what it was designed for (bass registers)…not sure I would pick it for an overall synth (though I would never give mine up heheh)

maybe have a listen to the volca bass/keys for something really cheap…you don’t have a lot of flexibility on them though…believe it or not, I still sequence mine into the mix now and then…even with A4, minitaur, etc…

better yet, maybe save up a while

once you get into the 1000-1500 range (usd) things really start to open up (I’m gas’ing for the sub37 myself)