I have always preferred the large canister filters over the HOB filters. That being said, there are a few things to consider...
1) Budget --- If you can't afford to buy the right filter, you are already starting behind the 8-ball in my opinion. You can absolutely run a tank with a smaller filter, and simply do larger, and more frequent water changes. That takes me to #2.
2) Time --- Who has time to do a 50% water change once a week????? I am lucky if I can do that once a month....and it's usually 2 x 5 gallon pails worth. For those who have tanks 100 and up, you're talking 50 gallons EVERY WEEK! While I think this will definitely help maintain a cleaner tank, sometimes you need to just let nature handle its business. I've found that the less you mess with an established ecosystem, the better and healthier it runs.
3) Fishload --- My plan is to stock this 125 pretty heavy. I am aware of the possible pitfalls going in. That being said, this is not my first rodeo (I really do hate that expression. LOL!!!). I've been keeping fish for almost 30 years. I have had set-ups that ranged from the most basic, to the most elaborate. I think if you're going to purchase a big tank that houses big fish (and a lot of them), you need something a with a little more power and capacity than a hang on the back unit. For those who disagree with that statement, please refer back to my comments #1 and #2.
Thoughts? Comments?......Let's have it