I am definitely a tinker'er as well... more recreation than professional I would guess... I have the following on mine w/ Custel's that operates VERY stable:
HTC Home Plugin - Large Clock display/Organizer from Touch
HTC Home Customizer - Customizes Home Plugin
HTC Dialer - Optional Dialer from Touch
HTC Audio Manager - Optional Media Alternative from Touch
HTC 10 Button CommManager - Optional Comm from Touch
HTCustom - Another Customizer
Office Mobile - Stock
Windows Live - Removed
Voice Dial - Removed
TaskMgr - Task & Application Management tool
TCPMP - Needed for You Tube'ing videos
TCPMP Plugin V0.4.2 - Needed for You Tube'ing videos
Skunkworks VideoBundle - Needed for You Tube'ing videos
PCM Keyboard - Optional Touch Keyboard
Total Commander - Optional Registry Editor
SKTools 3.1 - PPC Cleaner, File Management & Registry Tool
Pocket Plus 4.0 - Today Plugin Organizer
Flashlite 2.1 - Allows for various animations, etc
Macromedia - Allows for various animations, etc
Touchflo V1.4.1 - Touch UI
TouchfloConfig - Configures TouchFlo on/off, gestures, etc
Google Maps 2.0 - Terrific Mapping Application
TouchPadVibrate - Vibrates Dial pad When Dialing
Plus I have the common tweaks and power registry edits and after ~20 hours plus of usage, I have 22.3MB of ROM stable...
But just like paravis said, it's all subjective and the end result will vary upon what/how YOU want your device to function and look.