Allagan weapon replaces Determination with Piety, and it gives slightly more spell speed than Thyrus.
I personally really like Piety, and I'd choose Piety over DET/spell speed any day simply just from personal preference.
What would I wear? Allagan cane probably. Why? Simply because I like piety as a stat, it shows content clear, and I like how it looks. (The thyrus glow doesnt do much for me, mainly because it doesnt glow while sheathed, so it feels kinda weird to me O_o)
Which one is better? Thyrus +1.
Take it for what you will.