I was in between 4 bikes, Mu, Tikit, Brompton and Birdy
Birdy
I have no chance to see them in a store let alone test them.
I have looked at websites, read forums and my impression for the best and worse aspects of each bike are as below :

Best aspects first:

Mu Price, standard components
Tikit Hyperfold, reported ride quality
Brompton Best folded shape and size, elegance, available accessories
Birdy Best design (it's a stunner ), best performance on various terrains, built quality, available accessories

Now the worse :

Mu Bland design (I know it's subjective), lack of vow factor, no specially designed accessories
Tikit Folded size ugly and unbalanced and big, reported flex
Brompton Not a good performer on all terrains, no sportier riding
Birdy Price, price, price !

I decided against a Mu because it did not pull a string in my heart. Even if it would be the best performer, the most quality built, the lowest priced (and that latter is true) , I would not care. A bike has to be loved since I will make love to it two times a day and it will be a long performance 15 km each way

I decided againt Tikit since I do not need extra 10 seconds or be that extra 30 seconds when folding/unfolding. Maybe I will miss a vehicle once in a year because of those seconds and who knows that vehicle would not have an accident later? We need to embrace life as it is and not push everything to be perfect anyway. Tikit is an handsome bike but I had mixed feelings and I know I do not need its special qualities.

I am thorn between Brompton and Birdy.
Though different, both won my heart by their design: I liked Bridy's hi-tech looks and expedition rack and built quality and good design; and I liked Brompton's elegance, understated, unpretentious looks that oozes quality.

For me a folding bike must fold in a neatest and smallest shape. Speed of fold/unfold may be 1 second or 1 minute I do not care. Brompton is excellent in that regard. Also its price compared to Birdy is far better as you know. However I would choose Birdy over Brompton if they were at the same price levels. So price, best folded size push me towards Brompton.

PS : I also intend to add an electric motor to the bike. Both accepts a kit. Birdy can be motorized on the back wheel by a Bionx 350 watt with unit on the expedition rack and it looks and performs exquisitely. Brompton can be motorized on the front wheel with a Nano 200 watt. I am OK with front wheel motor and Nano is nearly silent. Nano integration is easier and again lower priced. However both bikes are good with electric motor.