Good question, I went with a DIY LED fixture which I love. It's going on about 2 years now and I'm just now getting it tweaked out perfectly. Needless to say there is a huge learning curve to DIYing leds its like its own hobby, for me I love getting into projects so it was a no brainier. It sounds like I have the same tank as you a 4' 120gal so here's my led recipe. I have 4 channels of light wired into an apex dimming module, channel 1 24 UV leds, channel 2 16 cool blue xml 8 XTE royal blues 48 XRE royal blues, channel 3 10 red and 10 turquoise leds and channel 4 8 premium xpg leds. Note that out of 124 LEDs that only 8 of them are white xpgs. My experience with leds is that you can wash out the actinic look quick with white leds. When I pump up my xpgs full bore the tank looks 10k no joke. Here's how I cycle my channels. In an 11 hour photo-period it starts with 15 mins of UV from 15mins to 1.30 my blues ramp up from 1.30 to 2.00 my red and turquoise come on from 2.00 to 4.00 my xpgs come on at 1% power just lit from 4.00 to 5.30 my xpg ramp from 1 to 100% and then the cycle reverses its self back down.
For me a DIY light fixture offers flexibility and is very upgradable. LED technology is on the rise. I believe in the next few years well see better LEDS that are brighter and consume less power and with a DIY system you are able to evolve your system. Now on the other hand I know there are plenty of ready made led fixtures. If I were to go that route I would seriously wait till next year and get the new Radion XR30 pro. It would be the latest greatest led fixture and I believe its going to be exceptional based on the already proven Radion xr30. I can't speak for other brands as I don't know to much of them it sounds like people like the sol as well. Good luck on your quest and if I can help please feel free to ask.