I believe – but can't give a proof for it – the East and West Prussian Landwehr units were left in the east, because there were sufficient Landwehr units farther west to fill Blücher's army and which thus had not to march so far.
In my opinion, if you want to rate the Landwehr units by "quality", they shouldn't be grouped by provinces, but by regiments or better even battalions.
For example, some battalions of the 1. Westphälisches Landwehr-Infanterie-Regiment had a high percentage of volunteers in their ranks (I am not talking about the detachments of self equipping Freiwillige Jäger here), and according to the regimental history, in the 1815 campaign this regiment performed quite well.
On the other hand, the 5. Westphälisches Landwehr-Infanterie-Regiment had many deserters from the beginning, and parts of it broke at Ligny. However, I don't know of any regimental history or memoirs of members of this unit.
In late 1813, one battalion (I don't remember which one) of the 1. Kurmärkisches Landwehr-Infanterie-Regiment was ironically nicknamed "the brave battalion" – obvieously, the other battalions perforemd better.
Generally, I think the info available is too sparse and sometimes too one-sided to arrive at any just classification of these units.
If you still want to compare the Landwehr (or any other) units, you could create a formula for the ratio of strength, losses and deserters and maybe – if at hand – awards distributed after the campaign. Some numbers, though obviously not always correct:
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