The U-87Ai is a standard in most professional studios. The sound and behavior are familiar to both talent and production staff so they are easy to work with.
The M-149 can be described the same way.
While both mics are studio standards, they sound quite different. There is no way to recommend one or the other, without knowing more about the material you propose to record, the voice you propose to record, and the space in which you propose to record.
For most of us, and expenditure at the level of a U-87Ai or M-149 is significant enough to justify auditioning before buying. Equipment houses which are used to dealing with professional's home studios are in the habit of making such mics available for audition before purchase (some places charge a rental charge).
Give yourself a week of use of each, and if possible, of both together, to see which one works for your voice, in your room, on your material.
Once you get your new mic, don't think of it as a replacement for your AT 4033s, but rather as an addition to them. Now you have a three mic cabinet. Don't forget the 4033s when you have a need for which they are better than either the U-87Ai or the M-149.
Cordially,
Tom