I like the epic windrider with a celestial paragon pegasus mount personally.
The epic spellcasters are bland but powerful.
Epic spellsword would obviously advance the spell failure reduction chance 5% every other level, increase the channel spell ability every 4 levels (13th, 17th) and add 1 use per day for each 10 levels (11th, 21st) and have bonus feats every 3 levels (11th, 14th, 17) with +1 caster level every other level. Automatic quicken and automatic still spell practically replace the channel spell ability.