Like so many things in this sport (or addiction, you choose what to call it), it really does depend on your application.

The posts at the start of the thread saying any kind will work and the line does not matter as long as it sinks may hold true for casting out in a lake or pond to fish that are scattered through the water collum.

I just got back from fishing 20 days in Chile. Nearly 70% of fishing was done with a sinking line. Putting the fly in the strike zone matters. When fishing rivers especially with varying water depths and fish in heavy cover, fishing with a sinking line is demanding, and you have to tinker to get your presentation right. I would vary my sinking line for the application, and what was said above rang very true: You absolutly need to know how your line sinks, and reacts to both initial sink, and when you are stripping the fly. When a sinking line goes down it is in constant motion (sinking and being pulled by current). If it is only in the stike zone a short time, well your chances of success are going to suck. If it gets to the strike zone fast and stays there longer, you chances obviously are going to be much better in fooling a fish to eat that fly.

Another issue is casting. Being in a boat on an open pond or lake and flailing it out there and letting it sink is one thing. Being backed into nearly imprenatrateable brush and tring to roll cast a heavy sink line into a 30mph wind in your face when trying to get to spooky brown trout in heavy cover is a whole different thing.

I personally mostly use Teeny lines. There is a new Teeny professional series sinking line for streamers, the Kelly Gallup streamer line. This is 60 feet of full sink, and it really works good in the rivers to keep the streamer in the zone. It sinks at about 5ips, and is very thin, so has great wind resistance for casting, and rolls good once you get on to it. It also is moderately priced. The other Teeny sink lines I like is the Teeny Tip 175 for fast and shallow rivers, the T-300 and the Super Magnum Chuck and Duck for really going down like casting upstream of a very deep hole and having it drop right down on in. The TT-175 is a rocket in the wind, and you can get really nice line speed with it. The slower sink rate is great in shallow water, especially faster moving as the streamer flys stay where you want them to be....

I also am partial for lakes to a Rio 24 foot Density Compensated 300 grain. This line casts real nice, either overhand or roll, and 24 foot at that weight goes down real nice. The density compensation means it pulls real nice and level when you strip as the tip sinks at different rates to compensate for being at different levels in the water collum (tip will always be lower).

If I had to pick two sink lines to have with me for the waters I fish (Alaska and Chile), it would be the Rio DC and the Teeny Kelly Gallup.

Just my two pescos (cents).