Making sure you have the next putter you buy custom fit to you has more to do with your stroke mechanics than the putter itself. Spending more does not guarantee better results. Tiger Woods will tell you its the sound a putter makes when he hits the sweet spot. The putt stroke is made up of hierarchical steps like a series of domino's. If they are all aligned, you can push over the first one and the others will fall in line. The first step is a neutral set up. Therefore, the number one criteria in choosing your next putter is having a putter custom fit so it consistently puts you in your neutral set up when you stand over a putt. Whether it is a blade, mallet or hybrid involves your stroke dynamics. Part of custom fitting is getting a face balanced putter. A toe weighted putter corrects for a stroke flaw. If you have your putter custom fit, you will not need to correct for a stroke flaw so a face balanced putter is the way to go. Next, you have to feel comfortable with the look of your putter. If you don't like the way it looks you will not putt well because it undermines your confidence in your new putter. Aiming lines assist in ensuring you hit the sweet spot. The bigger the better. Lastly, Tiger Woods is right, you must be able to hear the sweet spot so it is repeatable.
Let's recap, whatever putter you choose needs to be custom fit to you. A face balanced putter assists in a pure in line stroke. You have to like the way it looks. The bigger the aiming line the better. Lastly, hitting the sweet spot should cause a sound and feel that is repeatable.