Ranking from worst [1] to best [10]
Learning curve
VB [9] Delphi [7] C++ [2]
VB is a snap to get started, Delphi is not bad, C++ sorry
Cross platform Support
VB [1] Delphi [3] C++ [8]
VB = MS, say no more. Delphi (Kylix) can run on Linux, but support is spotty. C++ runs everywhere, you just have to handle a lot of platform specific issues in your code.
Performance
VB [6] Delphi [8] C++ [9]
VB is actually decent these days. Biggest performance problems are lack of support for more advanced operations needed for tuning. Delphi is quite good, but lack of tuning options, etc. make it hard to tweek an app with some problems. C++ is about as fast as you get without assembly
Ease of Development (simple gui apps)
VB [9] Delphi [7] C++ [2]
If your needs are basic, VB is about as easy as it gets.
Ease of Development (complex gui apps)
VB [5] Delphi [8] C++ [2]
But, when you run into walls with VB, Delphi just keeps moving along
Ease of Deployment
VB [2] Delphi [8] C++ [9]
VB practically invented DLL ****. Dephi usually does not have this problem. Neither does C++, and you usually know exactly what is in your C++ app.
Component Based development
VB [7] Delphi [10] C++ [1]
You can find most components you want for VB. You can use all of these plus some very nice Delphi only components in Delphi. And in Delphi, you can write components (and you can almost always get the source for native Delphi components you find). C++ -- we don't need no stinking components.
Library Availability
VB [2] Delphi [4] C++ [8]
Both VB and Delphi libraries are fairly sparse (there is a little more open source and equivalent for Delphi). You can find just about anything for C++, biggest problem is library compatibility problems.
Programmer Availability
VB [9] Delphi [3] C++ [6]
You can't swing a dead cat without hitting a VB programmer. C++ programmers are less common these days cause many of them switched to Java. Delphi is just not as popular
Expert Programmer Availability
VB [4] Delphi [5] C++ [3]
Experts are hard to find. VB tends to draw amateurs, Delphi and C tend to attract experts. Problem is expert C++ is very difficult to achieve. C++ is a very difficult language to master
Job satisfaction
VB [2] Delphi [7] C++ [5]
Most VB's seem to find themselves in a stale position. C++ can be a lot a fun, but it has a tendency to be terrible complex, making for late nights, etc. Delphi is really quite a bit of fun to use
Hacking Fun
VB [1] Delphi [4] C++ [9]
Serious hacker ignore VB, some like Delphi (but its GUI is negative), hard to beat hackability of C++, though templates sometimes cause serious bloat.
Platform Risk
VB [9] Delphi [3] C++ [10]
VB / C++ are here to stay (these app will be supported for a long time). Delphi may be in trouble, there is little reason to consider the dotnet version unless you have existing Delphi codebase.
Career Path Risk
VB [6] Delphi [4] C++ [6]
VB is here to stay as is C++. C++ is being replaced mostly by Java over time.
Overall if you are writing moderately complex Window Apps, Delphi is first choice, VB follows, and C++ is much worse.