Ok, your question is very loaded.
I use a half-dozen different apps depending on what I want to do.
Nero is a good, general-purpose burning app. However, if you want FREE or CHEAP there are other apps that do everything Nero does.
For ripping and also for burning image files, DVD Decrypter is still tops.
For transcoding, DVD Shrink is free, Nero Recode is a more advanced version of DVD Shrink (same author, only he works for Ahead now), or CloneDVD is good if you like Elby/Slysoft's style.
For ripping DVD's, DVD Decrypter was/is king, but is no longer being produced so you may want to consider AnyDVD from SlySoft (although it costs money).
What I personally use:
CopyToDVD/CopyToCD: For burning a VIDEO_TS folder into a video DVD, or for just taking a pre-built folder and dumping it immediately to CD/DVD. It can do more, but that's my primary use for it.
DVD Decrypter: For burning ISOs.
Nero: General purpose data backups, some ISO formats that DVDDecrypter doesn't do.
Shrink/Recode: Quick transcodes.
DVD Rebuilder+CCE: Better re-encodes.
Software I'm looking at:
Prassi: They used to make RecordNow, but now they have a newer and better burning engine. I forget the name of their new software but it's on my "download it and try it out" list.
Software I will NEVER USE:
Roxio: Never never never never NEVER NEVER NEEEEVVVVEEEER!
InCD: No packet-writing software shall ever defile the sanctity of my PC. Not gonna happen.
DVD X-Anything: Shitware even when it was being developed. Now sued into nonexistance but the affiliates still pimp it.
1-Shit DVD Crappy: Name says it all.