the answer depends on what you are trying to extract. If you want a wide array of compounds use a combination of solvents co cover a wide polarity range (but solvents need to be able to mix). Keep in mind that solvents used for this must be removed before usage in tests if your test subjects are sensitive to them or you will get a false positive ore negative results. Water, methanol, ethanol, acetone... are good picks because then diluted they can be used to work with cell lines but to work with proteins you need to be more selective with the pick. Try consulting the literature to see what others used to achieve the same objective.
I used different combinations of solvents:
pentane/hexane to get the more non-polar fractions - also very easy to remove by vacuum distillation of even leaving open over night
To carry out plant materials extraction you consider the phytconstituents of interest and select solvent with respect to the polarity. Aq.Methanol is ideal for extration of different polarity of phytconstituents. N-hexane is suitable for essential and fixed oil. Chloroform, ethyl acetate and 1:1 methanol-methylenechloride will extract moderate polar phytconstituents.