I'm a thrifty guy. I prefer not to spend money on unnessary things. That being said, I highly recommend the use of a pH controller.
I've used the Milwaukee's for years, and they are great. So much more control over your CO2. Prior to owning/using one, I had a few bad experiences of gassing my fish. Haven't had a problem since I started using pH controllers.Can you have a great tank, with dialed in CO2, without a controller? Sure, but it's a lot easier with one. I've written many a love affair posts about pH controllers in the past.
Finally, I've used Milwaukee's for years and they've been great, but that being said I bought a Pinpoint for my 120g....that thing is amazing.
Note: I bought all mine used, and got a good deal on all of them. (Think I've never paid more than $50 for the Milwaukees, and got the Pinpoint for $65). However, after using them for years, if one of them died and I had to buy a new one, I'd be willing to pay full price because they are that luxurious.