It might be a bit premature yet to give a final judgment, but I can tell you what I've observed so far.
I started off with DSL because it was cheaper, long-term, than cable. There's also the fact that I somewhat resent the cable company and would love like to dump cable entirely. (Unfortunately, the local dish offerings carry even fewer of the stations I want, and I can't even tune in most of the "local" stations with just an antenna.)
So I got DSL, and it was fine for a few years until I started working from home. Here's the deal: you're supposed to put a filter on any device that's connected to the phone line (other than the DSL modem). Otherwise, DSL noise will get through on your voice line, which can make conversation difficult.
Anyway, the DSL performance was pretty good and very reliable. I noticed some slowness when using the phone and the Internet at the same time, but it wasn't a big problem until I started working at home.
I use a VPN client to connect to my employer's network. I don't need it all the time, or even most of the time, but I do need it. I noticed that any phone activity - ringing, dialing, talking, whatever - would cause the VPN connection to drop. (I don't know whether that was due to voice noise interfering with the DSL, or if it was a bandwidth problem.) I could work around this to some extent, but when you're in the middle of a lengthy file transfer, you do not want some idiot fax machine from Canada to wreck the whole thing!
And sometimes (but not always), I would have trouble viewing WebEx sessions while dialed in on a teleconference. I could work around this by calling in on my cell phone, but it got to be very annoying.
Also annoying was the constant hiss on my phone line, which the DSL filters were supposed to eliminate.
After Googling around a bit, I discovered that if you have a burglar alarm that's connected to your phone line, it needs a filter too. That never occurred to me, and Verizon never mentioned it. IT'S IMPORTANT. It has cost Verizon and other DSL providers some (admittedly not much) business. There's still nothing about it on their website, as far as I can see.
First, I tried to resolve this with Verizon. I was very happy with the talk we had, but it turned out that they had badly misunderstood my request. I still don't know what they thought I wanted them to do, but I can tell you that it should NOT have involved interrupting my phone and DSL service on and off for several hours. Especially without warning me first. In fact, I was so angry with them that I was ready to switch my phone to Comcast too, just out of spite.
I asked several people what they thought of Comcast's phone service, and as a result, I decided to forgive Verizon.
But the VPN connection was still getting dropped. Verizon told me that they couldn't do anything about my burglar alarm, and I'd have to ask the alarm company to install the DSL filter. Protection One told me they'd be happy to do that for a fee, but since I wasn't even sure it would solve my problem (it would get rid of the hiss, but what about the VPN getting dropped?), I wasn't willing to pay what it would cost.
So I went to the Comcast website and ordered HSI from them. I wasn't at all impressed with the ordering process - you fill out a form on their website, which is simple enough, and then you have to wait and wait and wait for a CSR to "chat" with you to confirm that you really do want to place the order. She said it was for "security." I wish there had been a better way. The chat interface sucks - you have to keep that tab of your browser out where you can see it, because it won't flash in your taskbar or anything when the CSR finally shows up.
It all got done quickly enough, however, and I had my cable modem and "installation kit" three days later. The instructions and installation diagram were pitiful; fortunately, I knew what I was doing. Then I inserted the "installation wizard disk," which didn't work, and I had to call Customer Support.
At that point, I wondered if I would need a stiff drink. I was sure I'd either end up speaking to an unhelpful moron, a person reading from a script in such a thick accent I wouldn't be able to understand anything, or god forbid maybe an unhelpful moron reading from a script in a thick accent. It'd be an hour if I was lucky.
Instead I ended up with a bright and helpful person named Ryan who figured out what was wrong, rebooted my "moodem" (yes, he did have a thick Canadian accent, but somehow we were able to converse), did a couple of other things, and that took care of it. This took about 20 minutes.
So far, I've found cable Internet to be much moodier, speedwise, than DSL. It's often somewhat chuggy during peak times (which are fortunately not the hours when I'm working). My VPN connection is hanging in there, though, and it's pretty nice to be able to pick up the phone without hearing a loud hiss and getting network errors all over the place.