I have been using subsonic and the issues i keep running into is with when i make schema changes, I have to recompile everything and at times subsonic does not recognise some of the schema changes.
Is there a better OR/M that i can use asp.net which is more efficient with working with schema changes
I never had any problems with class generation with SubSonic. Are you sure your schema is a good one? Do you follow the conventions? If some tables are not generated, you may be missing PKs, but if you look into the generated classes it will tell you (in a comment) that this is the case. That's all the advice that I can give based on the information provided by you. I still think it's not SubSonic that's the problem...
If you are using the BuildProvider there is known issues with that and you might have to edit the web.config sometimes for it to rebuild, you can also try using SubCommander (sonic.exe) to generate your classes for you.
You can also try NHibernate check out http://www.summerofnhibernate.com/
What Database are you using and what schema changes are not showing up. In my experience with SubSonic I have never had any schema changes not show up in the generated classes. The largest error that I have seen people make is to add a table to their database, run the SubCommander to generate their classes and then forget to include the generated class in their project.
The only other related issue I have seen people make is if you generate your classes in a seperate class and they are all generated in C# and the project that is using the classes is written in VB. VB can not read into a C# project so you first need to build your C# project to see the schema changes in your VB project. That is one of the limitations of VB.
I suggest LLBLGen PRO. It is not free but well worth the $$$. I have been using it for more that 4 years on both web and windows applications.