FlyMaster+ 140 Dernier, 100 yards $2.00
Danville Threads have the brightest colors. 140 Denier is generally a good thread size for mid size flies, I use it for sizes #8 to #2. That will vary depending on your preference for thick thread verses thin thread.
The Flymaster+ has good Fluorescent colors and 140D is the right size for my #10 Glow-Bugs, Nuke Eggs and my smaller Yarn Bubble Eggs.