^ I'm in a similar situation. I would go AIO but I don't necessary like the ones out at the moment. So here is what I'm doing..
I like nice rimless tanks so I opted for an ADA 60P (24"x12"x14"). Then I got a custom black abs plastic AIO box to fit into the side of the tank (4"x12"14"), giving me 20"x12"x14" for the display. The AIO unit has a return where I put probes in, a second section for a tunze 9002 skimmer and 50W heater, then the last chamber is where I put the ATO and the return pump.
So for this setup, I bought.. (prices are for new and used stuff)
1. ADA 60p tank $200
2. AIO custom box $50
3. Tunze 9002 skimmer $100
4. 50W heater $25
5. Vortech mp10es $175
6. Kessil a150 $200
You can of course change a few things out. I like this route because it gives a good looking rimless tank, simple AIO concept, and custom-ability, and costs just as much or a bit more compared to other AIO units out there..
Hope this helps