Being bored one day whilst the EU servers were down, I decided to crunch some numbers with regards to how efficient the various housing options were in regards to storing your stuff:
Name : The name of the structure
Item : The number of item stacks that can be stored
Cap. : The bulk capacity
Area : The total area, in square metres (1 world unit = 1 metre)
X, Y : The extent of the structure, in metres
I/A : The number of items per square metre (Item / Area) - Higher is better
C/A : The bulk capacity per square metre (Item / Area) - Higher is better
Name
Items
Capacity
Area
X
Y
Items/Area
Capacity/Area
Fiendish Large House
60
4500
600
24
25
0.100
7.500
Dwarven Small House
30
2750
216
18
12
0.139
12.731
Dwarven Large House
55
4250
550
25
22
0.100
7.727
Sslik Medium House
50
4000
525
21
25
0.095
7.619
Saris Tiny Hut
25
2000
120
12
10
0.208
16.667
Saris Manor House
70
5250
828
36
23
0.085
6.341
Saris Medium House
50
3750
486
27
18
0.103
7.716
*Human Large House
60
4750
667
29
23
0.090
7.121
Human Medium House
60
4750
702
27
26
0.085
6.766
Human Hut
40
3250
330
22
15
0.121
9.848
Sslik Tiny Hut
25
2500
182
13
14
0.137
13.736
Tier 1 House
20
1500
49
7
7
0.408
30.612
Tier 2 House
40
3000
294
21
14
0.136
10.204
Tier 3 House
60
4500
608
32
19
0.099
7.401
Tier 4 House
80
6000
1008
42
24
0.079
5.952
Tier 5 House
100
7500
1595
55
29
0.063
4.702
Tier 6 House
120
9000
2176
68
32
0.055
4.136
Human Guild House
150
11000
1054
31
34
0.142
10.436
Tier 1 Guild House
60
4685
256
16
16
0.234
22.207
Tier 2 Guild House
120
9375
576
24
24
0.208
16.276
Tier 3 Guild House
180
14000
2500
50
50
0.072
5.600
Tier 4 Guild House
240
18750
2500
50
50
0.096
7.500
Tier 5 Guild House
300
23450
5625
75
75
0.053
4.169
Tier 6 Guild House
360
28125
5625
75
75
0.144
5.000
Cloth Tent (Blue or Brown)
10
450
39
6.5
6
0.256
11.538
(edit: [code] tags seem to ignore things like newlines/carriage returns, so here's a fugly table instead [;)])
(another edit: added the Cloth Tent entry to the bottom. Please note the X/Y measurements are fairly rough, but close enough given the funky footprint of these eyesores[8-|])